Preparation of polypentenamers is well known using a catalyst comprising an organoaluminum compound and a tungsten salt (U.S. Pat. No. 3,790,545). It is known that 1-olefins may be used to adjust molecular weight of polypentenamers (U.S. Pat. No. 3,684,781). The prior art also teaches use of alkanes, cycloalkanes and aromatics as suitable polymerization solvents. Prior art reactions begin instantaneously upon mixing of monomer and the complete catalyst, making difficult the exact control of polymer uniformity. Thus prior art polymers often contain substantial amounts of gel and are often difficult to remove from polymerization vessels. A new polymerization process is desired having a brief induction period to allow better process control and production of substantially gel-free polymers.